Mischmetal block.
A large block of "mischmetal", a mixture of lanthanum, cerium, and a few other random rare earths. Blocks like this are used for spark effects in movies. It is incredibly sparky stuff, here I'm holding it up to a small grinding wheel. The "Spin" and "Rotate" videos show this in action.Source: eBayContributor:Theodore GrayAcquired:16 April, 2009Text Updated:16 April, 2009Price: $30Size: 3"Purity: <20%